1. Field of the Invention
The present invention relates to a connector structure having an electric terminal for flowing a large current, in more particularly, to a connector structure having a male terminal and a female terminal in that the male terminal is connected to the female terminal by inserting the male terminal into the female terminal.
2. Description of the Related Art
Nowadays, HEV (Hybrid Electric Vehicle) attracts a great deal of interest, since the HEV can provide an effect of reducing exhaust of harmful gas and a large fuel saving benefit. A connection between an inverter and a motor for driving the HEV is conducted by a connector, and a large current greater than 100 A may be flown in accordance with the system of the HEV. In accordance with development in electrical control techniques of the vehicles, a large number of connectors have been used for the vehicles. However, there are few kinds of connectors that are suitable for the large current flow. As examples of terminals used for the connectors suitable for the large current, a flat-plate shape male terminal shown in FIG. 11 and a flat-plate female terminal shown in FIG. 12 are proposed.
As shown in FIG. 11, a male terminal 50 composed of a single narrow plate member comprises a wire connecting portion 51 at one end thereof, to be connected to another electrical apparatus (not shown), and an inserting contact portion 52 at another end thereof, to be contact with a female terminal shown in FIG. 12. At the wire connecting portion 51, a device connecting hole 53 for fastening and tightening the male terminal 50 with a bolt to the other apparatus. Dimensions of the male terminal 50 are e.g. a width of about 95 mm and a thickness of about 1.2 mm.
As shown in FIG. 12, a female terminal 60 formed by bending a plate member comprises a terminal energizing portion 61 for fixing and electrically coupling the male terminal 50 thereto, and a wire clamping portion 62 for connecting an electric wire by clamping. In the terminal energizing portion 61, a plate spring 63 for fixing the male terminal 50 within the terminal energizing portion 61 is provided.
As shown in FIG. 13, when the male terminal 50 is inserted into the female terminal 60, the inserting contact portion 51 of the male terminal 50 is pressed by the plate spring 63 and attached securely into the terminal energizing portion 61, so that the male terminal 50 and the female terminal 60 are electrically connected with each other.
The male terminal 50 and the female terminal 60 shown in FIGS. 11 to 13 are made of a high conductivity material (i.e. a material having a high electrical conductivity), for example, copper. Among the copper materials, it is preferable to use the high conductivity copper material, so as to suppress generation of heat when the current is flown.
However, since a relationship between an electrical conductivity and strength of the terminal material is a trade-off, there is a tendency that the strength of the terminal is reduced when the high conductivity material is used for forming the terminal.
For example, if the terminal is formed by using a copper with a conductivity of 90% or more, a desired strength of the terminal cannot be obtained. Accordingly, it is necessary to form the terminal by using a material having a sufficient strength, while sacrificing the conductivity of the terminal material to some extent.
Since the female terminal 60 is provided with the spring 63, it is necessary to select the terminal material with considering that the spring 63 thus formed should have a sufficient elasticity, in addition to the relationship between the conductivity and the strength of the material.
The material having excellent characteristics for all of the conductivity, strength, and elasticity is not found currently. However, as the means for solving the above problems, there is proposed a female terminal with a configuration of combining a terminal energizing portion with a high conductivity and a spring with an excellent spring characteristic and a high strength, in which the spring and the terminal energizing portion are fabricated separately and combined with each other.
Conventional male terminal structures are disclosed by Japanese Patent No. 2878429 (JP-B-2878429), Japanese patent No. 2993590 (JP-B-2993590), and Japanese Utility Model publication for opposition No. 7-51739 (JP-Y-7-51739).
However, since the conventional male terminal 50 shown in FIG. 11 is composed of a single plate, a surface area there of is small, so that the heat dissipation property is not excellent. Accordingly, there is a disadvantage in that a temperature of the terminal is elevated during the large current flow, thereby influencing on a housing resin or peripheral devices of the connector.
Further, there is proposed a male terminal having a hollow structure with a rectangular cross section to increase a surface area and a cross sectional area of the male terminal, so as to enhance the heat dissipation property. However, in the case where the male terminal having the hollow and rectangular shape is used, while the heat dissipation during the current flow can be improved, it is difficult to conduct a bus connection which is typically used in the connection with a component at the device side such as an inverter. It is because that the terminal at the device side may be bent to have an L-shape when used for the bus connection in accordance with the system configuration. In such a case, it is significantly difficult to bend the terminal with the rectangular structure for the bus connection, since cracks may be generated. Therefore, the problems in the conventional male terminal cannot be solved by the hollow and rectangular structure male terminal. In addition, conventional female terminal structures are disclosed by Japanese Patent Laid-Open No. 11-233182 (JP-A-11-233182) and Japanese Patent Laid-Open No. 2005-56792 (JP-A-2005-56792).
However, when the conventional female terminal is used as a connector terminal for a vehicle, there is a following disadvantage. The connector terminal for a vehicle may be exposed to a high temperature such as 150° C. In such circumstances, a terminal box (terminal energizing portion 61) of the female terminal may be opened when a material composing the terminal has a large stress relaxation property. For example, a plate member bent with an angle of 90° may be deformed in an opposite direction as a result the plate member may be opened to have an angle of around 100°.
When the terminal box is opened, a distance between the spring and the terminal box is increased, namely, a space to which the male terminal is inserted is enlarged. In such a case, an amount of displacement applied to the spring is decreased, namely, a contacting force of the spring for pinching the male terminal is reduced, so that the electric apparatus connected via the female terminal 60 does not satisfy a predetermined characteristic.
Accordingly, it is necessary to form the female terminal in which the contacting force of the spring is set be high at a normal temperature, with considering an opening angle of the terminal box at the high temperature, such that the predetermined characteristic of the female terminal can be obtained even though the terminal box is opened due to the high temperature. However, when the spring with high contacting force is provided, there is a disadvantage in that a force required for inserting the male terminal into the female terminal (terminal inserting force) is increased, so that the insertion of the male terminal into the female terminal will be difficult.